appendices to the model description document for a … · 2013-08-30 · svhser 10638 appendices to...

EDTECHNOLOGIES

NASA Contractor Report 181738

SVHSER 10638

APPENDICES TO THE MODEL DESCRIPTION DOCUMENT

FOR

A COMPUTER PROGRAM FOR THE

EMULATION/SIMULATION OF A SPACE STATION

ENVIRONMENTAL CONTROL AND LIFE SUPPORT SYSTEM

By¸

HAMILTON STANDARD

DIVISION OF UNITED TECHNOLOGIES CORPORATION

WINDSOR LOCKS, CONNECTICUT

PREPARED UNDER CONTRACT NO. NASl-17397

FOR

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

LANGLEY RESEARCH CENTER

HAMPTON, VIRGINIA

September 1988

G3/Sa

N89- I 3895

gnclas

0183244

https://ntrs.nasa.gov/search.jsp?R=19890004524 2020-06-26T22:10:20+00:00Z

_ UNITEDTECHNOLOGIES SVHSER 10638

ABSTRACT

A Model Description Document for the Emulation Simulation Computer Model was

published previously. The model consisted of a detailed model (emulation) of

a SAWD CO2 removal subsystem which operated with much less detailed(simulation) models of a cabin, crew, and condensing and sensible heat

exchangers. The purpose was to explore the utility of such an emulation/

simulation combination in the design, development, and test of a piece of ARShardware - SAWD.

Extensions to this original effort are presented in the manual. The first

extension is an update of the model to reflect changes in the SAWD controllogic which resulted from test. In addition, slight changes were also made to

the SAWD model to permit restarting and to improve the iteration technique.

The second extension is the development of simulation models for more piecesof air and water processing equipment. Models are presented for: EDC,

Molecular Sieve, Bosch, Sabatier, a new condensing heat exchanger, SPE, SFWES,Catalytic Oxidizer, and multifiltration. The third extension is to create two

system simulations using these models. The first system presented consists of

one air and one water processing system. The second system consists of a

potential Space Station air revitalization system complete with a habitat,laboratory, four modes, and two crews.

L

', r

{L 'i


FOREWARD

This Model Description Document has been prepared by Hamilton StandardDivision of United Technologies Corporation for the National Aeronautics and

Space Administration's Langley Research Center in accordance with ContractNASI-17397, "Development of an Emulation/Simulation Computer Model of a SpaceStation Environmental Control and Life Support System (ECLSS)". This manual

describes the analytical models used in the three computer simulation programs

developed under this contract.

Appreciation is expressed to the Technical Monitors, Messrs. John B. Hall, Jr.and Lawrence F. Rowell of the NASA Langley Research Center for their guidance

and advice.

This manual was written by Dr. James L. Yanosy, Program Engineer, with

assistance from Mr. Stephen A. Giangrande. The extensions to the program

presented in this manual were performed under the direction of Mr. John M.Neel, Program Manager. Thanks is given to Mr. Joseph M. Homa for his efforts

in the development of the Space Station Model.

ii


TABLE OF CONTENTS

SECTION

A.OA.1

A.2

A.3

Bo

B.

B.B.

B.

B.B.

B.

B.B.

B.B.

B.B.

B.B.

B.

B.B.

B.

C.

C.C.

C.

C.

C.C.

C.C.

0

1

23

3.1

3.2

3.33.4

3.53.6

3.73.7.1

3.7.23.7.3

3.7.43.7.5

3.7.5.1

3.7.5.23.7.5.3

3.7.5.4

0

i

23

3.1

3.23.3

3.43.5

TITLE

LIST OF FIGURES ......................................

LIST OF TABLES .......................................

INTRODUCTION .........................................

REFERENCES ...........................................

APPENDICES

ESCM UPDATE ..........................................Introduction .........................................

SAWD Bed .............................................

SAWD Control Model ...................................

MODEL DESCRIPTION DOCUMENT FOR ECLSB MODEL ...........

Introduction ...........Modelling of System.[_[[[[[[[[_[_[_...[[[[[[[_[[[_[

Modelling of Components ..............................SPE Cells ............................................

Catalytic Oxidizer ...................................

Sabatier CO2 Reduction Subsystem ...................EDC CO2 Removal Subsystem ..........................VCD Water Processing Subsystem .......................Filtration Models ....................................

Control ..............................................

Nitrogen Addition Control ............................

Oxygen Production Control ............................

CO2 Partial Pressure Control .......................Cabin Temperature and Humidity Control ...............Water Tank Level Control .............................

Urine and Wash Water Storage Tank ....................

Clean Hygiene Water Storage Tank .....................Potable Water Storage Tank ...........................

Condensate Water Storage Tank ........................

SPACE STATION MODEL ..................................

Introduction .........................................

Modelling of System ..................................

Modelling of Components ..............................Molecular Sieve ......................................

Bosch.

Plate Fin Condensing Heat Exchanger ..................Control

PAGE

iv

v

1

2

A-i

A-1

A-1A-2

B-i

B-1B-2

B-4

B-5

B-IOB-11

B-16B-22

B-23B-23

B-26B-26

B-27B-27

B-28

B-29

B-29B-31

B-33

C-i

C-1C-2

C-17

C-18C-26

C-34C-37

C-43

iii


LIST OF FIGURES

FIGURENUMBER TITLE PAGE

B-1

B-2

B-3

C-1

C-2

C-3

C-4

C-5

C-6

C-7

C-8

C-9

C-lO

C-11

C-12

C-13

C-14

C-15

C-16

ECLS System B Schematic for G189 Type

Computer Model .......................................

Catalytic Oxidizer Subsystem Schematic ...............

EDC CO2 Removal Subsystem Schematic ..................

Space Station Model Overview .........................

Space Station Nodes ..................................

Overview of Habitat ARS ..............................

Overview of Laboratory ARS ...........................

Habitat Cooling Packages .............................

Laboratory Cooling Packages ..........................

Habitat Oxygen Generators ............................

Laboratory Oxygen Generators .........................

Habitat CO2 Removal Units ..........................

Laboratory CO2 Removal Units .......................

Habitat CO2 Reduction Units ........................

Laboratory CO 2 Reduction Units .....................

Habitat Catalytic Oxidizers ..........................

Laboratory Catalytic Oxidizers .......................

Molecular Sieve Subsystem Schematic ..................

Bosch Process Subsystem Schematic ....................

B-3

B-12

B-17

C-3

C-4

C-5

C-6

C-7

C-8

C-9

C-10

C-11

C-12

C-13

C-14

C-15

C-16

C-19

C-27

iV


LIST OF TABLES

TABLE TITLE PAGE

B-I

B-2

B-3

B-4

B-5

B-6

SPE Cell Operating Efficiency ........................

SPE Cell Voltage .....................................

Listing of GPOLY1 for ECLSB Model ....................

Listing of GPOLY2 for ECLSB Model ....................

Schedule for Dumping into Urine and Wash Water

Storage Tank .........................................

Usage Schedule for Potable Water Tank ................

B-7

B-8

B-24

B-25

B-30

B-32

_ UNITEDTECHNOLOGIES

1.0 INTRODUCTION

SVHSER 10638

The purpose of the original ESCM program was to demonstrate the

utility of an emulation simulation computer program in the design,

development and test of a piece of life support equipment. The piece

of life support equipment selected for emulation was the SAWD CO 2

removal subsystem. A continuation of the effort called for an update

of the computer model following testing of the SAWD unit. In

addition, extensions to the contract called for the development of

"lightweight" or low fidelity simulation models of contending life

support equipment and the configuring of this equipment into two

different systems.

This document provides three appendices to the original

description document[l]*. The appendices are:

model

me

B.

C.

Emulation Simulation Computer Model Update

Life Support System Model

Space Station Model

The following errata were found in the original document:

(I) Cover page: Report number should be SVHSER 9504.

(2) Page 25, fifth line: Should be "HA : Total enthalpy of gas

entering header, Btu"

*Numbers in brackets denote references listed in Section 2.0


2.0 REFERENCES

SVHSER 10638

(I)

(2)

Yanosy, J., "Model Description Document for a Computer Program

for the Emulation/Simulation of a Space Station Environmental

Control and Life Support System (ESCM)", Hamilton Standard Report

SVHSER 9504 for NASA Langley Research Center, NASA CR-181737, September

1988.

"G189A Generalized Environmental/Thermal Control and Life Support

System Computer Program Manual", McDonnel Douglas Corporation

MDAC-G2444; September, 1971.

(a) Yanosy, J., "User's Manual for a Computer Program

Simulation of a Space Station Environmental Control and

Support System (ECLSB)", Hamilton Standard Report SVHSER

for NASA Langley Research Center, September, 1986.

for the

Life

10630

_ UNITED

TECHNOLOGIES SVHSER 10638

APPENDIX A

ESCM UPDATE

A-i


A.I Introduction

SVHSER 10638

The Space Station Environmental Control and Life Support System

(ECLSS) Emulation/Simulation Computer Model (ESCM) has been updated to

include: (1) the capability of restarting the SAWD CO2 removal

subsystem from a transient start-up, (2) placing clamps on the SAWD

bed segment temperature when iterating the bed segment temperature

during the energy balance of the bed segment, and (3) the addition of

an energy balance control method where the amount of CO2 on the bed is

determined from the time for

detected by the flow sensor.

a change made to the control

updates to ESCM as they pertain to the Model Description Document

presented in this Appendix.

the CO2 to begin coming off the bed as

Thls latter change was made to reflect

logic in the hardware. Each of these

are

A.2 SAWD Bed

The capability to start the SAWD subsystem without first running the

steady state analysis was incorporated into the IR45 subroutine. The

inlet and exit heater parameters, as well as SAWD bed segment

parameters (i.e. temperature, pressure, molecular weight, and flow

rates) were initialized in the IR45 subroutine; in a similar manner,

they are initialized in the STEADY subroutine which is only called by

IR45 in steady state. Therefore, the SAWD CO2 removal subsystem can

be started from a transient start-up as well as a steady state

start-up.

A-I

_ UNITEDTECHNOLOGIESI_rlrL_'@l_ SVHSER 10638

Additional logic was also added to the IR45 BALANCE subroutine.

Limits were placed on the SAWD bed segment temperature while iterating

on the bed segment temperature for an energy balance of the segment.

One of the limits employed was as follows: if the temperature

entering the bed segment was greater than the $AWD bed temperature at

the start of the time step, then the resulting bed segment temperature

must increase,

A.3 SAWD Control Model

A new control method has been incorporated into the SAWD CO2 removal

subsystem model (IR45). This type of control uses an energy balance

control scheme as opposed to the relative humidity method which as

previously used. The energy balance method uses energy principles to

determine the absorption time of the next cycle based on the bed's

past desorb cycle. The total amount of energy for desorb can be

calculated form the amount of steam added to the bed during desorb.

The amount of CO2 desorbed from the bed is known from techniques using

the accumulator on the flow sensor; thus, the energy required to

remove the CO2 form the bed can be calculated. Also, the energy

required to heat up the bed resins and canister before the desorption

of CO2 can be calculated. Therefore, from an energy balance, the

amount of energy to heat the water which was on the bed at the start

of the desorb can be calculated. Thus, the bed water loading at the

start of the desorb can be determined. Knowing the amount of water on

A-2


SVHSER 10638

the bed at the start of the desorb, the next absorption time can be

determined. The following SAWD control logic has been incorporated in

ESCM Subroutine GPOLY1 to determine the absorb time.

Control Constants (Set in subroutine GPOLY1):]

KO - 1.11

KI - 0.045

KI6 - 115.01

K41 - 0.25

K42 = 2.5

K43 1 60.0

K44 1 3.808

K46 1 0.6996

K47 - 7480.0

K48 = 60.87

K49 - .00028205

KSO = 0.0034246

K51 - 1085

K52 - 157.37

K53 - 4.3167

K54 - 0.040259

Input:

C02TIME - Time CO2 goes to cabin during desorb, minutesDETIME - Time for desorption, minutesINT1 - Previous INT1 value.

NEWABTIME - Previous absorb cycle time, minutes.

ONTIME - Time steam generator is on during desorption, sec.

P . Accumulator pressure at end of desorption, sec.PH2OPAST - Past value of bed loading for this bed. %.

TIN - Inlet temperature at end of desorbing bed's post absorbcycle, F

TOUT - Exit temperature at end of desorbing bed's pastadsorbing cycle, F

A-3


A11 the following calculations are done at the end of desorption.

Calculate Bed CO2 loading fraction which was at start of this

desorb "FC02".

Power

Power

TSAT

T3

T3

Ratio

FC02

FC02

- ONTIME/(O.05769 * DETIME)

= Clamp (Power, 1, 1040)

. K54 * P**2 + K53 * P + K52

- K16 * (TSAT - 212)/Power

- Clamp (T3, 0.0, 17.5)

= (C02 Time - T3)/DETIME

- K51*RATIO**2+KSO*RATIO-K49

- Clamp (FC02, 0°0, 0.05)

Calculate Bed H20 loading percent which was at start of this desorb

"PCTH20".

WGTH20 = (KO * ONTIME - K46 * (TSAT-TIN) - K47 * FC02 - K48)/

(TSAT-TOUT) - K1 * DETIME - K44

OCTH20 - 100.0 * WGTH20

IF((PCTH20 - OCTH2OPAST).LT.-3.O) PCTH20 = PCTH2OPAST-3.0

IF((PCTH20-PCTH2OPAST).LT.-3.0) PCTH20 _ PCTH2OPAST-3.0

PCTH20 - Clamp (PCTH20, I0.0, 40.0)

Calculate new absorb cycle time, "NEWABTIME" in minutes.

A-4


INTI

INTI

NEWABTIME -

NEWABTIME -

NEWABTIME -

K41 * (PCTH20 - 25.0) + INTI

Clamp (INTI, -35.0, 35.0)

K43 + K42 * (PCTH20 - 25.)

NEWABTIME + INT!

Clamp (NEWABTIME, 20., 90.)

SVHSER 10638

The steam flow rate determines the desorption time.

steam flow is not calculated based on the relative humidity in

cabin during the previous absorption cycle. The steam flow for

next desorption of the bed is based on the steam flow rate during

past de,orb multiplied by the calculated steam generation power ratio.

The control of the

the

the

the

MSN " MSO * PR

The steam generator power ratio is set equal to 1.0 for the first

desorption of each SAWD bed. For all subsequent desorptions, the

power ratio is calcu]ated by squaring the actual time of the last

desorptlon and dividing it by the product of the calculated time of

the last desorption and the calculated time of the new desorption

time.

PR - ta * ta

tco * tcn

A-5

UNITEDTECHNOLOGIES

where:

SVHSER 10638

MSN

MSO

PR

ta

tco

tcn

= New bed desorb steam flow, pph

: Old bed desorb steam flow, pph

- Steam generator power ratio

= Actual time of last bed desorb, sec

= Calculated time of last bed desorb, sec

= Calculated time of next bed desorb, sec

A-6

_ UNITED


APPENDIX B

MODEL DESCRIPTION DOCUMENT FOR ECLSB MODEL

B-i


B.I Introduction

SVHSER 10638

An extension to the original ESCM program is to develop lightweight

simulation models of various life support equipment and to combine

them into a system. The utility of using all lightweight models to

enhance system design could then be explored. This differs from

the original program which was to investigate the utility of a

combined emulation and simulation model.

This manual provides the model description for one of the systems

simulated. This system consists of one air revitalization group of

equipment working in conjunction with one group of waste water

processing equipment. The principal pieces of equipment are:

Function Subsystem

CO2 Removal

CO2 Reduction

02 Generation

Trace Gas Removal

Condensate Processing

Urine Reclamation

Electrochemical Depolarized Concentrator

Sabatier

Static Feed Solid Polymer Electrolysis

Catalytic Oxidizer

Multifiltratlon

Vapor Compression Distillation

B-1


B.2 Modellin_ of System

SVHSER 10638

The life support system to be analyzed is shown in Figure B-I. The

following discusses how this system represents real hardware.

The system shown in Figure B-1 consists of many components;

however, some are the same. Therefore, models of only the

following components are needed:

(1) Crew (8) EDC Cells

(2) Cabin (9) Fan

(3) Fan (10) Splitter

(4) Heat Exchanger (11) Mixer

(5) SPE Cells (12) All Purpose Component

(6) Catalytic Oxidizer (13) VCD

(7) Sabatier

These components are arranged as required for use with G189A.

Accordingly, particular items are arranged for modelling purposes

but do not represent their actual physical location. First of all,

the crew which consumes oxygen and produces carbon dioxide and

water vapor is placed in series with other components before the

cabin. This was done to keep the schematic simple and to minimize

the number of components required. In actuality, the crew is in

the cabin.

B-2

_ UNITEDTECHNOLOGIES ORIGINAL, PAGE IB

OE POOR QUALIT_

SVHSER 10638

/--

FIGURE B-1ECLSS SYSTEM B SCHEMATIC FOR G189 TYPE COMPUTER MODEL

B-3


In the mode] in Figure B-l, it appears that the cabin has only four

ports for gas flows - two entry and two exit. This is a restric-

tion of G189A and again does not represent actuality. Air for the

condensing heat exchanger, Sabatier cooling and the EDC are all

drawn directly from the cabin. Since G189A has a limited number of

ports, one port is used and then splitters are used to direct flow to

each of the components. The end result is the same.

B.3 Modelling of Components

As discussed in Sectlon B.2, only thirteen component analytical

models need be available to analyze the life support system. The

following sections will discuss these analytical models, the

generation of performance constants, and any other parameters

necessary to describe the analytical model. In many instances, the

analytical model is already described in the G189A manual [2]. In

those cases, the reader will be referred to the G189A manual for a

description of the analytical model.

In addition to the thirteen components, the control of the cabin

air conditions and the water tank leve|s are discussed.

B-4


Of the thirteen components, many were discussed previously in the

ESCM Model Description Document [1]. The followlng are discussed

here:

SPE Cells

Catalytic Oxidizer

Sabatier

EDC Cells

VCD

Bacteria Filter

Charcoal Filter

Multifiltration

Controls

B.3.1 SPE Cells

The solid polymer electrolysis cells convert water to hydrogen and

oxygen and give off heat to a heat exchanger with the coolant being

air. The following constants and operating conditions are used:

Ac = unit cell area - 0.239 ft2

Pc = cell operating pressure - 200 psia

Tc = cell operating temperature = 155°F

Nc = number of cells - 20

The cell current density is determined from:

Jc " I/Ac

where I = cell current, amps

Jc = cell current density, amps/ft 2

B-5

UNITEDTECHNOLOGIES_/A_8_7@_

SVHSER 10638

A cell efficiency is then determined by linear interpolation of

the tables in Table B-1 for the cell pressure Pc, current density

Jc, and cell temperature Tc. In addition, the voltage Vc across

each cell is determined by linear interpolation of the tables in

Table B-2 for the cell pressure Pc, current density Jc, and cell

temperature Tc.

The total watts consumed by the cells becomes:

we - I Vc Nc

where Vc - voltage across each ce11, volts

we - total electrical power of cells, watts

The amount of oxygen and hydrogen produced is given by:

where:

m02 - 0.000659 I Nc

mH2 - m02/8

m02 - mass flow of oxygen produced, Ibm/hr

mH2 - mass flow of hydrogen produced, Ibm/hr

The water consumed by electrolysis is given by:

mH20, E - 1.125 m02

B-6


TABLE B-1

SPE CELL OPERATING EFFICIENCY

Percent Efficiency at Tc - 140OF

Cell Pressure (psia)

J(AMPS_FT 2) 100 200 300

50 91.1 84.7 82.7100 95.0 90.0 86.4

150 96.8 93.5 90.3200 97.5 95.1 92.6

250 98.0 96.0 94.0

300 98.3 96.6 94.9

350 98.6 97.2 95.7400 98.7 97.6 96.2

450 98.9 97.8 96.7

500 99.1 98.1 97.0

Percent Efficiency at Tc - 180OFCell Pressure (psia)

J(AMPS_FT 2) 100 200 300

50 87.8 82.4 79.0

100 93.0 86.7 82.9

150 95.4 90.7 86.3

200 96.6 92.9 89.1250 97.2 94.2 91.2

300 97.7 95.1 92.6

350 98.0 95.8 93.7400 98.3 96.4 94.5

450 98.4 96.7 95.1500 98.0 97.1 95.6

B-7

B UNITEDTECHNOLOGIES

TABLE B-2

SPE CELL VOLTAGE

SVHSER 10638

J

(AMPS_FT 2)

5O

100

150200

25O300

350

400

Cell Voltage at Tc = 140OFCell Pressure (psia)

i00

1.5561.5941.6231.6501.6781.7141.7601.832

200

1.568

1.6021.632

1.6621.690

1.725

1.772

1.843

300

1.577

1.609

1.6381.667

1.697

1.733

1.777

1.857

J(AMPS_FT 2)

5O100

150200

250

3OO350

400

Cell Voltage at Tc - 180OFCell Pressure (psia)

100

1.5031.5371.5621.5871.6141.6391.6701.701

200

1.5141.5481.5731.5991.6241.6511.6821.722

300

1.522

1.553

1.5811.606

1.6321.657

1.6891.728

B-8


where: mH20, E - mass flow of water consumed by electrolysis,

Ibm/hr

Water is also present as saturated vapor in the oxygen and hydrogen

gas flows.

The amount is determined from the following relation:

Psat(Tc)

Yv "

Pc

Yv m02

MH20,02 : _1-Yv MW02

MWH20

Yv mH2

MH20,H2 - _ --1-Yv MWH2

MWH2

where: Yv " mole fraction of water vapor

MW02 - molecular weight of oxygen, Ibm/mole

MWH2 - molecular weight of hydrogen, Ibm/mole

Psat " saturation pressure at given temp., psia

mH20,02 - mass flow of water vapor in oxygen, Ibm/hr

mH20,H2 - mass flow of water vapor in hydrogen, Ibm/hr

Therefore, the total water consumed becomes:

mH20, T - mH20, E + mH20,02 + mH20,H2

B-9

_ UNITEDTECHNOLOGIESMA_IllL_@M

The waste electrical power is given by:

SVHSER 10638

ww = we (1 - 1.48 _ /Vc)

The heat given off to the ambient is given by:

Q - (ww + 0.11 we + 27.3) 3.413

where Q I heat lost to ambient, Btu/hr.

All this heat is transferred to a heat exchanger which is cooled by

ambient air.

B.3.2 Cata1_tic Oxidizer

The model of the catalytic oxidizer is a simple model which com-

putes the temperature of the air stream exiting the unit. The

composition of the air remains unchanged. The following constants

are used:

Wht r - heater power - 28 watts

Mc - mass of high temperature bed catalyst - 2.0 Ibm

Tc - operating temperature of high temp. catalyst - 600OF

s - fraction of air flow to high temp. catalyst - 0.1111

HX " heat exchanger effectiveness I 0.9

Cp = specific heat of air , 0.24 Btu/Ibm-F

B-IO


First the temperature leaving the high temperature bed is computed

as:

Th I Tc - _HX (Tc - Ti)

where Th - exit temp. from high temp. bed, OF

Ti I air inlet temp. to cat ox., OF

This high temperature air mixes with the air not going to the high

temperature bed to give the resultant exit temperature.

Te I

s m I Th Cp + (l-S) m I TI Cp

m i Cp

Figure B-2 shows a schematic of the catalytic oxidizer subsystem

and the location of the above discussed temperatures and flows.

B.3.3 Sabatier CO? Reduction Subsystem

The Sabatier CO2 reduction subsystem consists of the Sabatier

reactor, a fan and a water separator as modeled for G189A.

A listing of the

User's Manual [3].

provides the gas composition

temperature of the cooling air

heat exchanger.

Sabatier subroutine SABHS is given in the ECLSB

The model is a simplified block box model which

exiting the reactor and the mixed

leaving the reactor and condensing

B-11

_ UNITED

TECHNOLOGIESSVHSER 10638

mis

mi T i

mi(1 -s)

i HTCO

Assembly

ToT h

ATCO TiAssembly

HTCO=High Temperature Catalytic Oxidizer

ATCO=Ambient Temperature Catalytic Oxidizer

mev

FIGURE B-2

CATALYTIC OXIDIZER SUBSYSTEM SCHEMATIC

B-12


The Sabatier reaction is assumed to go to completion. First a test

is made on the incoming gases to determine whether excess hydrogen

or carbon dioxide exists. The reaction is:

CO2 + 4 H2---_-CH4 + 2 H20

If mH2,1 <

2.016

then excessive

consumed.

4 me02, i

44.01

carbon dioxide exists and all the

For thls case, the following relations hold:

hydrogen is

mCH4, e - mH2,i MWCH4

4 MWH2

mH20, e - mH2,i

4 MWH2

2 MWH20 + mH20, i

mH2,e - 0.0

mc02, e - mc02, i - mH2,1

4 MWH2

MWc02

Qsen = 8864. mH2,i

4 MWH2

B-13


where:

SVHSER 10638

mH2,i = mass flow of hydrogen entering reactor, Ibm/hr

mH2,e = mass flow of hydrogen exiting reactor, Ibm/hr

mc02, i = mass flow of carbon dioxide entering reactor,

lbm/hr

mc02, e = mass flow of carbon dioxide exiting reactor,

Ibm/hr

mCH4, e = mass flow of methane exiting reactor, Ibm/hr

mH20, e = mass flow of water exiting reactor, Ibm/hr

mH20, i = mass flow of water entering reactor, Ibm/hr

MW = molecular weight, Ibm/mole

Qsens . sensible heat produced by reaction, Btu/hr

On the other hand, If excess hydrogen exists, the following

relations hold:

mCH4, e = mc02, i MWCH4

MWc02

mH20e = mc02, i

MWc02

2MWH20 + mH20,i

mc02, e = 0.0

mH2,e = mH2,i - mc02, i

MWc02

4MWH2

B-14


Qsens = 8865. mc02, i

MWc02

4MWH2

The latent heat load to condense the water produced is

QLAT I 1050. mH20, e

The temperature of the cooling air leaving the Sabatier is:

Tair,e " Tair,i + (Qlat + Qsens)/mair Cp

where: mai r . mass flow of air, Ibm/hr

The fan draws air around the reactor for cooling and through a

condensing heat exchanger to condense the product water. The fan

operational characteristics are:

cfm I 20.0

power - 34 watts

The condensed water and product gases pass through

separator which is modeled as an alternate component for use

G189A. All the water is separated from the product gases and

Btu/hr is added to the product gases in the form of heat.

a water

with

0.13

B-15I


B.3.4 EDC CO2 Removal Subsystem

SVHSER 10638

The EDC CO2 removal subsystem removes carbon dioxide from the air

stream through a rue| cell type process which requires hydrogen and

produces electriclty. Heat is removed through a water cooled heat

exchanger. Again, simple black box models are used. See Figure

B-3 for a schematic representation.

A 1istlng of the EDC subroutine EDCHS is contained in Appendix A of

the ECLSB User's Manual [3]. The following constants are used:

Jd

RC02

Ac

Tc

Pc

- design current density I ii Amps/ft 2

- CO2 transfer rate - 0.001736 Ibm C02/amp-hr

- area per cell - ft2/cel]

. cell operating temperature - 70OF

= cell operating pressure = 14.7 psia

cpc02 - 0.211Btu/Ibm-F

CpH2

cp02

NC

- 3.437 Btu/Ibm-F

: 0.221Btu/Ibm-F

. number of cells = 30

First, the carbon dioxide removal at design conditions

ca|cu|ated using the following:

iS

mco2,d = RC02 Jd Ac Nc

B-16


SVHSER 10638

m H2,i + m H20,vi

m02,i+ mN2,i

+m H20,i + m co2,i

tHeat Exchanger

H20 Coolant

J

v

I'II 0.75 Qsens

II

EDC

To, Pc

mH2,e+ mCO2,A + mH20,ve

mo2,e+ mco2,e + mN2,i + mH20,e

FIGURE B-3

EDC CO 2 REMOVAL SUBSYSTEM

B-17


Then, a factor is computed for use in determining the actual CO2

removed. This factor is given by:

I JA + 0.27 I 1JC02" -JD ..... 1.27

The actual CO2 removed becomes:

mc02, A - mc02, d KC02

mc02, e - mc02, i - mc02, A

where: JA - actual current density,amps/ft 2

mc02, i - mass f_ow of CO2 into EDC, lbm/hr

mc02, e - mass flow of CO2 exiting EDC in air stream, Ibm/hr

The actual electrical characteristics required are:

I - 1.27 KCO 2 JD AC

V - JA

JD

0.5 Nc

dividing line on separate half space

w.lV

B-18


In the process, oxygen is

following relations:

consumed; the amount is

SVHSER 10638

given by the

PC02 =mc02,1 Pi

MWc02

760

14.696

= 1.02 + 0.19

PC02

0.718

2PC02

MC02, c =

MCO2,A MW02

2 MWco 2

mo2,e = m02,i - m02,C

where: Pi = inlet pressure of air to EDC, psia

mc02, i = inlet mass flow of CO2 into EDC, Ibm/hr

MWc02

PC02

R

MW02

m02,C

m02,i

mo2,e

= molecular weight of CO2 = 44.011bmlmole

= partial pressure of CO2 in inlet air, mm Hg

= effectiveness of conversion

= molecular weight of oxygen = 32 Ibm/mole

= mass flow of oxygen consumed, Ibm/hr

= mass flow of oxygen into EDC, Ibm/hr

= mass flow of oxygen exiting EDC air stream, Ibm/hr

B-19


The factor of 2 in the preceding equation arises from the overall

reaction taking place in the EDC cells:

CO2 + 1/2 02 + H2 .... > CO2 + H20 + electricity + heat

Accordingly, the amount of hydrogen consumed is given by:

m02c MWH2

mH2,C - 2 ....MW02

The amount of water produced is:

mH20,PmH2,c MWH20

MWH2

Some of the water available leaves with the hydrogen and carbon

dioxide gases. It is assumed that the vapor is saturated and that

the pressure in the H2-CO 2 exit port is 20 psia. The amount of

water leaving with the H2-CO 2 mixture is given by the following:

mH2,e - mH2,i - mH2,C

mWmi x = mH2,e +mco2,A

mH2,e + mco 2

MWH2 MWc02

B-20


PV = Psat(Tc)

- MWH20 PV

MWmix PT - PV

SVHSER 10638

MH20,VE :cu{mco2,a + mH2,e)

mH20, e : mH20, p + mH20,i + mH20,Vi - mH20,ve

where: mH2,i - mass flow of hydrogen into EDC, lbm/hr

mH2,e - mass flow of hydrogen exiting EDC, Ibm/hr

MWH2 .mo]ecular weight of hydrogen, Ibm/moles

MWH20 - molecular weight of water, Ibm/moles

MWmi x . molecular weight of H2-CO 2 mix exiting EDC,

Ibm/moles

Pv - vapor pressure of water in H2-CO 2 stream, psia

Psat - saturation pressure for given temp, psia

cu : humidity ratio

PT . total pressure in H2-CO 2 exit line, psia

mH20,ve - vapor leaving with H2 and CO2, Ibm/hr

mH20, i - mass flow of water into EDC from air stream,

Ibm/hr

mH20,vi - mass flow of water into EDC with H2 stream,

Ibm/hr

8-21


The total heat generated is given by:

Qd " 65.7 + 766.8 mc02, d

Qsens = (1.06 KCO2 - 0.06) Qd

where: Qd . design heat production, Btu/hr

Qsens " actual heat production, Btu/hr

Of this heat, 25% is added to the air stream and 75% must be

removed by the heat exchanger. Accordingly, the exit air

temperature is given by:

Te - TI +

0.25 Qsens

(mair, i + mH20,vi ) ep

where: Ti - inlet air temperature, F

mair, i - inlet air flow, Ibm/hr

Cp - specific heat of inlet air - 0.24 Btu/Ibm-F

B.3.5 VCD Water Processin 9 Subsystem

Vapor compression distillation process purifies water through a

distillation type process. The model at present is simple and

determines the amount of power consumed and the amounts of water

and brine delivered. The following relations and constants are

used:

B-22


mH20, e - 0.96 mH20, i

SVHSER 1O638

mb - 0.04 mH20, i

where:

mH20,ew - 120

40.1

mH20, i - mass flow of water into VCD - 2.30 lbm/hr for 3

man units or 2.73 lbm/hr for 6 man unit.

mH20, e - mass flow of clean water exiting VCD, Ibm/hr

mb = mass flow of brine, ]bm/hr

w - power required, watts

B.3.6 Filtration Models

Three filtration devices are modeled in ECLSB by the use of the

Alternate Component subroutine. The three components are the

bacteria filter, charcoal filter, and multlfiltration. For each of

these, the inlet flows and conditions pass through unchanged.

B.3.7 Control

A variety of items require control to operate the system

effectively. CO2 and 02 levels in the cabin atmosphere need to be

maintained, and water levels in the various tanks need to be

regulated. This control logic is contained in subroutines GPOLYI

and GPOLY2, and listings of these are contained in Table B-3 and

Table B-4 respectively.

B-23

_ UNITEDTECHNOLOGIES__©_

SVHSER 10638

LISTING

SUBROUTINE GPOLYI

TABLE B-3

OF GPOLYI FOR ECLSB MODEL

THIS SUBROUTINE PROVIDES THE CONTROL LOGIC FOR SYSTEM "B" ECLS

SIMULATION USING THE GI89A COMPUTER PROGRAM.

I_PE STATEMENTS:

INTEGER ONCE

REAL MR,INOM

LOGICAL STEADY,CYCLIC,LTSIDE,OPEN,VCDON,MFTON

DIMENSION STATEMENTS:

DIMENSION V(1),K(1)

DIMENSION TURINE(8),TllWASH(I1),TSHOWR(2),TDRINK(8),TFOODP(_)

COMMON STATEMENTS:

COMMON /COMP/ DS(I_),N,NA1,NBt,NC,NCAB,NCFL,NEXT,NEXV,NK,

1 NKEX,NKS,NKT,NLFL,NP,NPASS,NPF,NPFT(6),NQ,NS,NSF,NSFT(6),2 NSTR(18),NSUBR,NV,NVT,¥(12)

COMMON /RARRAY/ IMAXR,R(02_O)COMMON /ECLSTI/ KCHOUT,KPRNT,KPTINV(4),KWIT,KWITI,KWIT2,

I I_ITS,KWIT4,NUFF,KSTED¥COMMON /KANDV/ K

COMMON /MISC/ DTIME,GRAV,KFLSYS,KOUTPT,KPDROP,KSYPAS,KTRANS,

I LPSUM(5),MAXCI,MAXLP,MAXSLP,MAXSSI,NCOMPS,NEWDT,NLAST,NPASPD,

2 MINSSI,PGMIN,PLMIN,START,STEAD¥,TIME,TIMEMX,TMAX,TMIN,WTMAX

COMMON /CASE/ NCASE,NRSCS,NRECS

COMMON /PROPT¥/ CPO,CP(99),CPCONL,CPCONV,CPCO2,CPDIL,CPOXY,CPTC,I GAMGAS,RHOO,RHO(99),VISCO,VISC{99),VISGAS,WTMO,WTM(99),Wl"MCON,

2 WTMDIL,WTMTC,XKO,XK(99),XKGAS,XKLIQ,VISLIQ

COMMON /SOURCE/ A(t9),B(tO),CPA,CPB,IAt,IB1,NA,NB,NPFS,NPFST(6),

! NSFS,NSFST(6),RHOA,RHOB,VISCA,VISCB,WTMA,WTMB,XKA,XKB

COMMON /VLOC/ IP,IS,IC,IQ,IV,IVT,IEX,INEXKCOMMON /LRC/ IDATE(2),ISCHM

DATA INITIALIZATION:

DATA TURINE / O.t,8.O,G.O,8.O,t2.O,t_.O,20.O,2_.O/

DATA THWASH / 0.1,8.0,5.0,6.0, 9.0,10.0,11.0,12.0,15.0,20.0,25./

DATA TSHOWR / 15.0,25./

DATA TDRINK / 0.1,8.0,6.0,9.0,12.0,16.0,20.0,25.0/DATA TFOODP / 0.1, 5., 10., 14., 25./

DATA KU,KH,KS,KD,KF / 1, 1, I, l, l/

EQUIVALENCE (V(1),K(t))

B-24

SVHSER 10638

CC

C

C

C

CC

C

INITIALIZE AT START OF STEADY STATE SOLUTION. DONE ONLY ONCE.

IF(STEADY .AND. KSYPAS .LE. 1) THEN

LTSIDE - .TRUE,

TCABO - 0.0

TDESO = 0.0

IFREQ - VV(2,184)NMEN = KK(1,16)

H2OADD = VV(2,128)

CYCLIC = VV(2,185) .GT. 0.9END IF

IF(N .EQ. 1) THEN

READ TABLE OF METABOLIC RATE VS MISSION TIME (24 HR CYCLE).

TIMCYC - AMOD(TIME,86400.)

MR - VALUE(I,TIMCYC,O.O)TCAB - VV(2,104)TCAB = 70.

QL - MR=480.+(MR/IO00.÷ IO.)*(TCAB-60.O)QLMIN = O.22*MR+2.6*(TCAB-60.O)

QL = AMAXt(QL,QLMIN)QS = MR-QL

R(66) - qsR(67) - QLR(82) - MR

END IF

IF(N .E_. 2) THEN

IFKSTEADY .OR. MOD(KSYPAS,IFREQ) .EQ. O) ISCIIM - 1R(181) - DTIME

R(182) = DTIME/60.

LIGHTSIDE - DARKSIDE?

IF(CYCLIC) THEN

TIMORB - AMOD(TIME,5400.)LTSIDE - TIMORB .LE. 2700.

END IF

NITROGEN ADDITION RATE

R(166) = 0.0

WCN = 0.0PT = R(4)

P02 - R(94)

IF(PT .GE. 14.819) GO TO 220

IF (PT .GE. 14.818 .AND. P02 .GE. 8.28) GO TO 220IF (P02 .LT. 8.09) GO TO 220

B-24a

I I'

SVHSER 10638

CCC

210

C220

CCC

CCC

C

C

REGULATORLOGIC.

IF(OPEN) GO TO 210

N2 OPENING CURVES.

WCN = VALUE(22,PT,O.O)OPEN - .TRUE.GO TO 220

N2 CLOSING CURVES.

WCN = VALUE(28,PT,O.O)IF(WCN .LE. 0.0) OPEN - .FALSE.

R(166) = WCN

OXYGEN AND H20 VAPOR ADDITION FROM SPE, LBM/HR

R(128) = H20ADD+VV(20,68)R(165) = V(IV÷2)

TRACE CONTAMINANTS ADDITION

END IF

IF(N .EQ. 81 THENIF(.NOT. STEADY .OR. KSYPAS .GE. 41 THEN

WSEC - VV(7,1)WPRI = VV(5,1)WTOT - WSEC÷WPRISR - WSEC/WTOTR(651 - SR

END IFEND IF

IF(N .EQ. 6) THENR(84) = 0.0IF(VV(7,68) .GE. 560.) R(84) - 1.0

END IF

IF(N .Eq. 91 THENIF(.NOT. STEADY .OR. KSYPAS .GE. 4) THEN

WSEC - VV(14,1)

WPRI - VV(16,1)+VV(28,1)+VV(21,1)WTOT - WSEC+WPRISR - WSEC/WTOTR(651 = SR

END IF

B-24bI I'

SVHSER 10638

C

C

C

C

C

17

1799C

18

1899

C

19

I999

END IF

IF(N .E_. 11) THENW8 - A(I)*R(72)/CPA

W8 - AMAXIIW8,A(I))R(66) - EXP(2.809-O.OO169*B(1))*WS*(O._2+O.OOO26*B(1))

END IF

EXTRACT CONDENSATE WATER.

IF(N .Eq. 18) THENR(67) - A(7)A(1) - A(1)-A(7)

A(7) - 0.0

CPA - (A(_)iA(8)+A(6)eCPCONV)/A(I)

END IF

IFtN .Eq. 1_) THENIF(.NOT. STEADY .OR. KSYPAS .GE. 4) THEN

WSEC - VV(16,1)WPRI - VVt2B,1)*VV(21,1)WTOT - WSEC+WPRI

SR - WSEC/WTOT

R(65) - SREND IF

END IF

IF(N .Eq. 16) THENR(84) - 1.0

IF(.NOT. LTSIDE) R(84) - 0.0

END IF

IF(N .NE. 17) GO TO 1799

IF(STEADY .AND. KSYPAS .LT. 4) GO TO 1799

WSEC - VV(21,1)

WPRI - VV(28,1)WTOT - WSEC÷WPRISR - WSEC/WTOTR(65) -'SR

CONTINUE

IF(N .NE. 18) GO TO 1899

R(84) - 1.0IF(.NOT. LTSIDE) R(84) - O.O

CONTINUE

IF(N .NE. 19) GO TO 1999R(84) - 1.0

IF(.NOT. LTSIDE) R(84) - 0.0

CONTINUE

B-24cI I'

SVHSER 10638

C2O

2099

C21

2199C

28

2899C

24

2499C

28

CC

C

IF(N .NE. 20) GO TO 2099INOM - R(72)

P02 - VV(2,94)R(69) - INOM

IF(P02 .CE. 9.1) R(69) - 0.9*INOM

IF(P02 .LE. 2.9) R(69) - 1.1*INOM

CALL SK(1,20,16)IF(LTSIDE) GO TO 2099R(69) - 0.0

CALL SK(0,20,16)CONTINUE

IF(N .NE. 21) GO TO 2199

R(65) - VV(20,65)CONTINUE

IF(N .NE. 29) CO TO 2899

PC02 - VV(2,100)R(68) - R(69)

IF(PC02 .CT. 8.0) R(68) - R(69)IF(PC02 .LT. 2.0) R(68) - R(69)

IF(LTSIDK) GO TO 2899R(68) - 0.0

CONTINUE

IF(N .NE. 24) CO TO 2499

R(65) - VV(28,65)CONTINUE

IF(N .NE. 28) CO TO 2899

EXTRACT CONDENSATE WATER.

R(67) - A(7)A(I) - A(1)-A(7)

A(7) - 0.0

CPA - (A(5)*A(8)+A(6)zCPCONV)/A(1)2899 CONTINUE

C

92 IF(N .NE. 82) GO TO 8299

CPA - CPCONLRHOA - RHO(1)

CPB - CPCONL

RHOE - RHO(1)

WTMA - WTM(I)

WTMB - WTM(I)VISCA - VISC(1)

VISCB - VISC(I)

XKA - XK(1)

_. B-24d I I'

SVHSER 10638

8299

C

85

C

C

C

C

C

C

8510

CC

C

C

C

XKB - XK(I)

CONTINUE

IF(N .NE. 85) GO TO 8599

URINE DUMP TO STORAGE TANK, LBM/HR

A(1) - 0.0

IF (NMEN .Eq. 8) WDMP - 17./7.

IF (NMEN .EQ. 6) WDMP - 26.28/7.TIMC¥C - AMOD(TIME,86400.)

IF(TIMC¥C .LT. TURINE(7)*8600..AND. KU .EQ. 8) KU - 1IF(TIMC¥C .LT. TURINE(KU)*8600.) GO TO 8510

KU - KU÷I

KU - MINO(KU,8)

A(1) - WDMP/DTIME*8600.

WASTE HAND WASH WATER DUMP TO STORAGE TANK, LDM/HR

WHWASH - 0.0

IF(TIMCYC .LT. THWASH(IO)*8600. .AND. KH .EQ. 11) KH - 1IF(TIMCYC .LT. THWASH(KH)*8600.) GO TO 8520

KH - KH*I

KH - MINO(KH,11)WHWASH - 11.5/10.

A(I) - A(1)+WHWASH/DTIME*8600.

WASTE SHOWER WATER DUMP TO STORAGE TANK, LBM/HR

8520 WSHOWR - 0.0

IF(TIMCYC .LT. TSHOWR(I)*S600. .AND. KS .EQ. 2) KS - 1IF(TIMCYC .LT. TSHOWR{KS)*8600.) GO TO 8580

KS - KS÷I

KS - MINO(KS,2)WSHOWR - 22.5

A(1) - A(I)+WSHOWR/DTIME*8600.

C8580

FLOW EXITING URINE WASH WATER STORAGE TANK, LBM/HR

R(1) - 0.0IF(R(69) .LE. 80.) GO TO 8540

VCDON - .TRUE.

GO TO 85508540 IF(R(69) .GE. 27.) GO TO 8550

VCDON - .FALSE.

8550 IF(.NOT. VCDON) GO TO 8599

IF(NMEN .EQ. 8) R(I) - 2.80

IF(NMEN .E_. 6) R(1) = 2.788599 CONTINUE

C

B-24e I I'

SVHSER 10638

41

4199

C

42

4299

C

46

CC

C

4610

4699C

56

5699

C

58

IF{N .NE. 41) GO TO 4199

H2OSPE - VV(20,67)R(1) - (WHWASH+WSHOWR)/DTIMEt86OO.*H2OSPE*WMFLT

CONTINUE

IF(N .NE. 42) CO TO 4299WSEC - (H20SPE+WMFLT)tDTIME/8600.

WTOT - WSEC÷WHWASH÷WSHOWR

IF(WTOT .LB. O.O) GO TO 4299SR - WSEC/WTOT

R(65) - SR

CONTINUE

IF(N .NE. 46) GO TO 4699R(I) - O.O

WDRINK - 0.0

TIMCYC - AMOD(TIMK,86400.)

IF(TIMCYC .LT. TDRINK(7)t8600..AND. KD .Eq. 8) KD - 1IF(TIMCYC .LT. TDRINK(KD)*8600.) GO TO 4610

IF (NMEN .Eq. 8) WDRINK - 19.56/7.

IF (NMEN .EQ. 6) WDRINK - 81.82/7.KD - KD*I

KD - MINO(KD,8)R(1) - WDRINK/DTIMEt8600.

FOOD PREPARATION WATER DUMP TO STORAGE TANK, LDM/HR

WFOODP - O.O

IF(TIMCYC .LT. TFOODP(4)t8609. .AND. KF .EQ. 5) KF - 1IF(TIMCYC .LT. TFOODP(KF)i8600.) GO TO 4699

KF - KF+I

KF - MINO(KF,5)

IF(NMEN .Eq. 8) WFOODP - 4.74/4.

IF(NMEN .E_. 6) WFOODP - 9.48/4.R(I) - R(I)+WFOODP/DTIME*8600.

CONTINUE

IF(N .NE. 56) GO TO 5699

WSEC - WMFLTWTOT - WSEC÷H2OSPE

IF(WTOT .LE. 0.0) GO TO 5699

SR - WSEC/WTOT

R(65) - SR

CONTINUE

IF(N .NE. 58) GO TO 5899

WMFLT - 0.0

R(I) - O.O

WPOT - VV(46,69)IF{WPOT .GE. 40.) GO TO 5810

B-24f-- I I'

SVHSER 10638

MFTON - .TRUE.GO TO 5820

5810 IF(WPOT .LE. 45.) GO TO 5820MFTON - .FALSE.

5820 IF(.NOT. MFTON) GO TO 5899IF(R(IOO)*DTIME/8600. .LE. R(69)) GO TO 5880R(1) - O.OWMFLT - R(IO0)GO TO 5899

5880 R(1) - R(IO0)5899 CONTINUE

C61

6199C

IF(N .NE. 61) GO TO 6199IF(STEADY .AND. KSYPAS .LT. 4) GO TO 6199TCAD - VV(2,104)TDES - V(IV÷28)TTOL - 0.1IF(ABS(TCAB-TDES) .LT. TTOL) GO TO 6199A1 - 0.025ITER - 1CALL ESTIM(R(65),TCAB,TDES,R650LD,TCABO,TDESO,Al,ITER,NSTR(I))R(6_) - AMAXI(R(65),O.O)R(65) - AMINl(R(65),O.9)CONTINUE

RETURNEND

B-24q

I I'

UNITED


TABLE B-4

C

C

C

1

CC

C

C

C

C

12_

CC

C

199

C

2

LISTING OF GPOLY2 FOR ECLSB MODEL

SUBROUTINE GPOLY2

COMMON /COMP/ DS(15),N,NA1,NB1,NC,NCAE,NCFL,NEXT,NEXV,NK,

I NKEX,NKS,NKT,NLFL,NP,NPASS,NPF,NPFT(6),NQ,NS,NSF,NSFT(6),2 NSTR(IS),NSUBR,NV,NVT,Y(12)

COMMON /RARRAY/ IMAXR,R(0260)

COMMON /ECLST1/ KCHOUT,KPRNT,KPTINV(4),KWIT,KWIT1,KWIT2,! KWITS,KWIT4,NUFF,KSTEDY

COMMON /KANDV/ K

COMMON IMISC/ DTIME,GRAV,KFLSYS,KOUTPT,KPDROP,KSYPAS,KTRANS,

1 LPSUM(5),MAXCI,MAXLP,MAXSLP,MAXSSI,NCOMPS,NEWDT,NLAST,NPASPD,2 MINSSI,PGMIN,PLMIN,START,STEADY,TIME,TIMEMX,TMAX,IMIN,WTMAX

COMMON /CASE/ NCASE,NRSCS,NRECS

COMMON /PROPTY/ CPO,CPC99),CPCONL,CPCONV,CPCO2,CPDIL,CPOXY,CPTC,

1GAMGAS,RHOO,RHOt99),VISCO,VISCt99),VISGAS,WTMO,WTM(99),WTMCON,

2 WTMDIL,WTMTC,XKO,XK(99),XKGAS,XKLIq,VISLIQ

COMMON /SOURCE/ A(19),B(19),CPA,CPE,IAI,IBI,NA,NB,NPFS,NPFST(6),1 NSFS,NSFST(6),RHOA,RHOB,VISCA,VISCB,WTMA,WTMB,XKA,XKB

COMMON /VLOC/ IP,IS,IC,IQ,IV,IVT,IEX,INEXK

DIMENSION V(I),K(1)

EQUIVALENCE (V(I),K(1))

LOGICAL STEADY

IF(N.NE.I) GO TO 199

CALC NET FLOWS DUE TO CABIN PRI & SEC FLOW LOOPS

SBC02 - 0.0

SBH20 - 0.0

CALC NET H20 VAPOR CHANGE

XH20 - R(70) - SBH20 = VV(18,67) + VV(28,75) + VV(20,68)CALL SV(XH20,2,1gT)

CALC NET 02 CHANGE

X02 - -R(68) - VV(28,78) + VV(20,66)CALL SV(X02,2,175)

CALC NET C02 CHANGE

XC02 - R(69) - SBC02

CALL SV(XC02,2,177)CONTINUE

- VV(28,79)

IF (N .NE. 2) GO TO 299

B-25

SVHSER 10638

299C

18

1899C

28

2899C

R(2) - 70.R(21) = 70.R(89) - 0.42R(98) - 46.R(104) - 70.CONTINUE

IF(N.NE. 18) GO TO 1899R(20) - R(67)R(21) - R(2)R(22) - 24.7R(28) - 24.7CONTINUE

IF(N.NE. 28) GO TO 2899R{20) - R(67)R(21) - R(2)R(22) - 24.7R{28) - 24.7R(68) - VV(26,68)CONTINUE

B-25a

: I I'


B.3.7.1 Nitrogen Addition Control

SVHSER 10638

Nitrogen is added to maintain the total pressure in the cabin at

a level of 14.813 psia. The same control as used and described in

the ESCM Model Description Document [1] is used in the ECLSB model.

B.3.7.2 Oxygen Production Control

The oxygen level is controlled by adjusting the electrical current

to the SPE cells according to the following:

P02 _ 3.1 psia I - 0.9 INOM

P02 _ 2.9 psia I - 1.11NO M

where: P02 . partial pressure of 02 in cabin, psia

I - current to SPE cells, amps

INOM - nominal current to cells - 22 amps

This nominal electrical current corresponds to a nominal oxygen

consumption rate for three men at 0.255 Ibm/hr.

B-26


B.3.7.3 CO? Partial Pressure Control

SVHSER 10638

At present, the EDC production current is not adjusted in response

to changes in the CO2 partial pressure in the cabin. The current

density is maintained at a constant 11.0 amps per square foot. The

user may change this control logic by making desired changes in the

GPOLY1 subroutine.

B.3.7.4 Cabin Temperature and Humidity Control

Control of cabin temperature and humidity is accomplished by

regulating the fraction of air flow from the cabin which passes

through the condensing heat exchanger. The more air through the

heat exchanger, the cooler the cabin should become. The technique

to regulate the fraction to the heat exchanger is described by the

following relations:

For IT1 - Tsl < 0.1°F

the fraction remains unchanged. Otherwise;

f = fl + 0.025

f2 - fl

TI - T2

and f is clamped between 0 and 0.9.

T1 - Ts

B-27


Where: f - new flow fraction bypassing heat exchanger

fl " last flow fraction

f2 " flow fraction prior to fl

T1 - last cabin temperature, OF

T2 - cabin temperature prior to T1, OF

Ts - set point cabin temperature, OF

This is tantamount to a straight integral control technique with a

varying integration gain constant.

The effects of this control on cabin temperature and humidity are

negated, however, by the logic in GPOLY2. GPOLY2 simply sets the

cabin temperature to 70°F, the humidity to 42%, and the dew point

to 46OF. This was done to give reasonable temperatures until a new

control low can be developed.

B.3.7.5 Water Tank Level Control

Four water tanks are used for storage of clean and waste water;

they are:

(I) Urine and Wash Water Storage Tank

(2) Clean Hygiene Water Storage Tank

(3) Potable Water Storage Tank

(4) Condensate Water Storage Tank

B-28


For each of these tanks, the calculations for the entering and

exiting water flows are presented in the following paragraphs.

B.3.7.5.1 Urine and Wash Water Storage Tank

The Urine and Wash Water Storage Tank receives water from crew

urination, hand washing, and showering. The amount of water for

each of these activities is considered to be dumped into the tank

over a period of one time step which is currently 120 seconds or

two minutes. Table B-5 gives the amount and time of day at which

water is dumped into the tank for each of these activities. This

table, of course, may be altered by the user by appropriate changes

to the logic in GPOLYI.

Flow will exit the tank only if the VCD unit is on. The VCD unit

turns on whenever the tank level is greater than 30 percent full

and turns off if the tank level falls below 27 percent fu11. When

the VCD is on, it draws water at 2.3 Ibm/hr for a three man unit

and 2.73 Ibm/hr for a six man unit.

B.3.7.5.2 Clean Hygiene Water Storage Tank

The Clean Hygiene Water Storage Tank receives water from the VCD

unit at the rate processed by the VCD. Water is used from this

tank for handwashing and showers and to supply the needs of the SPE

and Multifiltration units. Accordingly, water for handwashing and

B-29


SVHSER 10638

TABLE B-5

SCHEDULE FOR DUMPING INTO URINEWASH WATER STORAGE TANK

AND

Time of

Day

8:06 AM

9:0010:00

11:0012:00

1:00 PM

2:003:00

4:005:00

6:007:00

8:00

9:0010:00

11:00

12:00

1:00 AM2:00

3:004:00

5:00

6:007:00

8:00

Water Dumped (Ibm)

Urine Hand-

3 Men 6 Men wash

2.429 3.754 1.15

2.429 3.754 1.15

1.152.429 3.754 1.15

2.429 3.754 1.15

1.151.15

2.429 3.754 1.15

2.429 3.754 1.15

2.429 3.754 1.15

17.00 26.28 11.5

Shower

22.5

22.5

B-30


showers is drawn from the tank according to the schedule in Table

B-5. Again, all the water for a given time in the table is

presumed to be drawn over one time step, i.e., two minutes.

The water required by the SPE unit is given in Section B.3.1 by the

relation for mH20, t. The water required for the multifiltration

unit is 2.55 Ibm/hr. However, water is drawn from the Hygiene Tank

only if the condensate tank is unab]e to supply the multifiltration

needs.

B.3.7.5.3 Potable Water Storage Tank

The potable water storage tank receives water from the multlfiItra-

tion unit. The multifiltration unit is supplied by a water pump

which draws water from the condensate storage tank or the clean

hygiene water storage tank if the condensate tank has insufficient

water. The pump draws water at 2.55 Ibm/hr. The multifiltration

unit pump turns on when the tank level fails below 90% full and

turns off if the level rises above 45%.

Water is drawn from the tank for drinking and food preparation.

Again, the amount of water drawn for each of these activities is

considered to be drawn from the tank over a period of one time step

which is currently two minutes. Table B-6 gives the amount and

time of day for each of these activities.

B-31


TABLE B-6

USAGE SCHEDULE FOR POTABLE WATER TANK

SVHSER 10638

Time

8:06 AM

9:00

10:00II:00

12:00

i:00 PM2:00

3:00

4:005:00

6:007:00

8:00

9:0010:0011:00

12:00

1:00 AM2:00

3:004:00

5:00

6:007:00

8:00

3 Men

2.794

2.794

2.794

2.794

2.794

2.794

2.794

19.560

Water Used (Ibm)

Drinking6 Men

4.474

4.474

4.474

4.474

4.474

4.474

4.474

31.320

Food

3 Men

1.185

1.185

1.185

1.185

4.740

Preparation6 Men

2.370

2.370

2.370

2.370

9.480

B-32

1UNITEDTECHNOLOGIES

B.3.7.5.4 Condensate Water Storage Tank

SVHSER 10638

The condensate water storage tank receives condensate water from

the condensing heat exchanger and the Sabatier reactor water

separator. Water is drawn from the condensate tank as required by

the mult_filtration unit to supply the potable water needs. When

water is drawn, it is drawn at 2.55 Ibm/hr.

B-33

UNITEDTECHNOLOGIES SVHSER 10638

APPENDIX C

SPACE STATION MODEL

C-i

_ UNITEDTECHNOLOGIESIXIAI_rl_@_

C.I Introduction

SVHSER 10638

This manual provides the model description document for a Space

Station model which includes a habitat, laboratory, and four nodes.

Only the air revitalization equipment is modelled; waste water

management tanks and processing equipment are not included in the

model. The principal pieces of equipment are:

Subsystem Option Available

(]O2 Removal

CD 2 Reduction

O2 Generation

Trace Gas Removal

Condensate Processing

H3C, l_lecular Sieve

Bosch, Sabatier

SPE, K(I-I

Catalytic Oxidizer

Plate-fin shuttle type heat exchanger

Options are also available for hydrogen or CD 2 bussing.

C-1


C.2 Modelling of System

SVHSER 10638

Figures C-I through C-14 present the schematics of the system as

modeled using G189A. The following discusses how this system

represents real hardware. Further descriptions of the system can

be found in the User's Manual [4].

In these schematics, extra lines, mixers, and splitters are

inserted to provide the user with flexibility to select various

options without having to rewrite the programs. These lines do not

represent actual plumbing arrangeamnts of a Space Station. For

example, a duct does not exit the habitat then tee to t_o modes as

shown in Figure C-1. In actuality, a node is adjacent to the

habitat and a fan draws air directly from the habitat into the

node. Therefore, these are functional schematics and do not

represent actual plumbing.

C-2


P

P

P

S

P

LFAKA[;E

IA AKAGE

I

F I(KJRE C-1

SPA(_ STATION _ OVERVIEW

C-3


$9_A}_©AP4@SVHSER 10638

NODE 1

J

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f

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P I

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OUTLET

NODE 2

_ _J

li

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P I

s f

p I

NODE 4

----- m I

_P

FIGURE C-2

SPACE STATICgq NODES

C-4


F

{I}

oo

i

FIGURE C-3OVERVIL:W OF HABITAT ARS

C-5


I

0

0U

F I(RJRE C-4

OVERVILaN OF LAIK)RATORY ARS

C-6


F

I

FROM _!

CABIN

FROM rCABIN

FAN

9

107 I

_PP_- ]_ 191

I

COOLANT

50O

HX

92

H20 SEP.

97 HX

99

H20 SEP.

FROM CO 2 REMOVALAND CAT. OX

S 95

CONDENSATE

TO CO 2 REMOVAL

AND CAT. OX.

I

I

I

I

I TO

CABIN

I

I

I

I

TO

CABIN

FIGURE C-5

HABITAT CDOLIM3 PACK/_ES

C-7


FI

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FROM _ !

CABIN

FROM

CABIN=L

I

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COOLANT

_!s_FAN IS 307 |

P J_ HX

L_ o2_o Ts 1291/

u n _L_293H20 SEP S

COOLANT

I so9 1P _e P[eP

FAN o 308f _298 j_00

299 _,Y

H2 0 SEP_S

CONDENSATE

FROM CO 2 REMOVAL

AND CAT. OX.

TO CO 2 REMOVAL

AND CAT. OX.

TO

_- CABIN

TO

CABIN

F ICKJRE C-6LABORATORY COOLING PACKAGES

C-8


IN2 ; ---

P

0 2 - ,

II

]

_oc°°L'"Ti

02 GENERATIONS

COOLANTi507 •

l_,_x 1&

,Q

p!02143 GENERATION S

H20

l

_ 2

FIGURE C-7

HABITAT_ENGENERATORS

C-9


STA½D_D

SVHSER 10638

N 2

4

0 2 :

_F_V°_Pip P_Ip

I-IX342

QS

P

341

S '

P

GENERATION

P

s_OLA"_I_IpPIP

r 1

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02 GENERATION S

343

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H20

-_1

FIGURE C-8

_TORY _ _TORS

C-IO

_ UNITED


cq

0{.)

i

ca i;141

i-4

0

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0

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FI_ C-9

HABITAT CD2 _M3VAL UNITS

C-ll


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C-12

_ UNITEDTECHNOLOGIES_AB_OBT@_]

SVHSER 10638

0

FIGURE C-11

HABITAT CD2 REIX.L-TIONUNITS

C-13


I

00'

Z H

_HC_0 ,< _..10U

,lL

[

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U

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FlfiUREC-12

I.AIK)RATORYCD 2 _IONUNITS

C-14

UNITEDTECHNOLOGIES

SVHSER 10638

P J CAT. OX PKG. 1 P

"1111

CAT. OX PKG. 2

, 112i

II

P

FIGURE C-13

HABITAT CATALYTIC OXYDIZERS

C-15

_ UNITEDTECHNOLOGIESIXI£_O[L_@f_

SVHSER 10638

P

I CAT. OX PKG. 1311

P

P

CAT. OX PKG. 2312

P

v

v

FIGURE C-14

LABORATORY CATALYTIC OXIDIZERS

C-16


C.3 _v_dellin_ of Ccrnnonents

The following sections discuss the analytical models of the

ccmponents available in this Space Station model. Some of these

have been described elsewhere. The following lists the subsystemsand where they have been discussed.

SPE Appendix B

Catalytic Oxidizer Appendix BSabatier Appendix B

EDC Appendix B

The following subsystems are discussed below:

1Vblecular SieveBosch

IC£]H

Plate Fin Heat Exchanger

Control Logic

C-17


C.3.1 1V_lecular Sieve

l_lecular Sieve removes carbon dioxide from incoming air.constants are:

Some

th

P_nTMVIS

TMSGcfm

Pfan

HSG

= half cycle time - 60minutes

=m in. pressure of desorbingmole sieve bed = 1.0 psia=max. temperature of desorbingmole sieve bed = 360°F

=max. temperature of desorbing silica gel bed = 180OF= fan cfm = 23.25

= 11 in H20= fan efficiency = 0.35

=(]02 removal efficiency = 0.65

= enthalpy change for adsorbing silica gel bed = 1400Btu/Ib H20

= enthalpy change for adsorbing n_l sieve bed - 1800

Btu/Ib- compressor cfm- 1.05

In order to understand the analytical description, the schematic of

the molecular sieve subsystem shown in Figure C-15 should bereviewed.

C-18

_ UNITED

TECHNOLOGIES

SVHSER 10638

U_i,i

r-,,

--i l¢..) I_ r--: I-I

---t'e_N

8

b-

FIGURE C-15

MOLECULAR SIEVE SUBSYSTEM SCHEI_TIC

C-19

_ UNITEDTECHNOLOGIESH£1_I]_@IXI

SVHSER 10638

First, the temperture leaving the fan is computed by the following:

QFAN

T2 = T1 +

maCp

where: T2 = temperatures leaving fan, F

T1 = temperature entering fan, F

QFAN = fan power, Btu/lb

cfm _PFAN

QFAN " 3.4138.5

ma = air inletmass flow to fan, Ibm/hr

Cp = specific heat of air, Btu/Ibm-F

Next, the temperature of the process air leaving the adsorbing

silica gel bed is calculated from the following:

T3MAX = T2 +

Cp

msg =

T3MAX - T3

600 - th

T3 = T3 + msg _ t

where: _ = absolute humidity of air entering molecular sieve

T3max - maximum temperature of air leaving the adsorbing

silica gel bed, F

msg : change of air temperature leving silica gel bed

with time, F/sec

C-20

_ UNITEDTECHNOLOGIES__@_

At : simulation time step, sec

th - time into half cycle, sec

SVHSER 10638

After i0 minutes into the half cycle, the temperature of the air

leaving the silica gel bed is limited to T3max.

The water removed by the silica gel bed is:

MH20 - MH20 + (MH20,in) _ t

where: MH20 . mass of water removed by silica gel bed during

half cycle, Ibm

MH20,in - flow of vapor and entrained liquid entering

system, lbm/hr

Thus the assumption is that all the moisture entering the system is

adsorbed onto the silica gel bed. Now, the temperature and mass

flow of coo] dry air leaving the heat exchanger is:

T4 - Tcool + 5OF

where: Tcool - temperature of coolant water entering HX, F

T4 - temperature of air leaving HX, F

C-21


The heat transferred by the heat exchanger to the water is:

QHX = md Cp (T3 - T4)

where: md - mass flow of dry air which entered molecular sieve

subsystem, Ibm/hr

The air flows next to the CO2 adsorbing molecular sieve bed. The

temperature of the air leaving that bed is given by the following

calculations:

mco2,a - mc02,i E C02

MC02, a - MC02, a + mc02, A /%t

PCO2,e " PC02,i (1- EC02)

mc02, e - mc02, i (1 - EC02)

T5,MI N : T4 +

MCO2,a _hms

md Cp

rams ,,

T5,mi n - T5

1800 - th

T 5 - T5 + mms _t

C-22

_ UNITEDTECHNOLOGIESIX]AI@fI£7@IXI

SVHSER 10638

where: mc02, i - inlet C02 mass flow into molecular sieve bed, pph

C02 " C02 removal efficiency of molecular sieve bed

mc02, a . rate of CO2 adsorption, Ibm/hr

MC02, a - total mass of CO2 present on bed, Ibm

PC02,i " partial pressure of CO2 in inlet air, psia

PC02,e " partial pressure of CO2 in molecular sieve exit

bed, psia

mc02, e I exit CO2 mass flow out of molecular sieve bed, pph

T5,mi n - minimum temp. exiting molecular sieve bed, F

After 1,800 seconds into the half cycle, the exit temperature

cannot be less than Ts,mi n.

The process air then flows to the desorbing silica gel bed. The

temperature of the bed rises for the first 17 minutes, peaks, then

falls for 17 minutes until the temperature reaches a minimum

Ts,mi n. The equations are:

For the first 17 minutes:

where:

TMSG - T6

Msgd -1020 - th

T6 I T6 + Msgd At

t6 - temperature leaving, desorbing silica gel bed, F

Msg d - temperature change with time of airleaving desorbing

silica gel bed, F/sec

C-23


This temperature TG cannot exceed Tmsg.

For the next 17 minutes:

SVHSER 10638

Msgd =

T5,min - T6

2040 - th

T6 = T6 + Msgd At

For these 17 minutes, the air

T5,mi n. From 34 minutes into

cycle, the temperature exiting the desorbing silica gel bed is set

T5,min-

The properties of the alr leaving this silica gel bed are:

temperature is limited to a minimum of

the half cycle to the end of the half

to

PH20 = PSAT(T6)

MWH20 PH20

mH20 = md

MWd PT - PH20

Msg d = Msg d + mHS 0 At

where:

Of course, the mass desorbed is limited to the mass adsorbed from

PHSO = partial pressure of water vapor in air, psia

mH20 = mass flow of water leaving silica gel bed, pph

Msg d = mass of water desorbed from bed this half cycle, Ibm

the

previous cycle.

C-24


The electrical power to the desorbing silica gel bed is given by:

For th < 240 seconds

th £ 240 seconds

Wht r . 0 watts

Wht r . 657 watts

The average heat given up by the desorbing silica gel bed to the

cabin is:

46

Qsg .... (Tmsg - Tcab)290

where: Tca b - cabin air temperature, F

The final calculation is that for the mass of CO2 desorbed from the

molecular sieve bed. The following equations are used for th > 480

seconds.

R (T4 + 460)

144 Pmin MWc02

where:

f P8 10.769 cfmcMC02, d = [1.01 + 0.01 .... ] ....

_Pmin) "Lr7

R - Universal gas constant : 1545 ft-lbf/mole R

MWco 2 - Molecular weight of CO2 - 44 Ibm/mole

Pmin " Minimum pressure of desorbing molecular sieve, psia

P8 " Accumulator pressure, psia

cfm c - Compressor cfm C

mc02, d - Mass flow of CO2 desorbed, Ibm/hr

, C-25


For th < 480 seconds, mc02, d - O.

The tota] carbon dioxide desorbed during the present half cycle is

given by:

MC02, d = MC02, d + mc02, d _t

Of course, the total amount desorbed is limited to the amount of

CO2 that was orlginally present on the bed.

C.3.2 Bosch

The Bosch is a process that reduces carbon dioxide and hydrogen

carbon and water while giving off heat. The model

based on the one described in

schematic of the process is

reaction is descrlbed by:

the G189A Manual [2].

shown in Figure C-16.

to

used here is

A functional

The chemical

2H2 + CO2 .... > C + 2H20

A listing of the program is provided in the User's Manual

Appendices [4].

First the molecular weight of bone dry condenser exit gas and the

inlet molar flows of H2 and CO2 are computed.

C-26

' UNITEDTECHNOLOGIES

SVHSER 10638

H 2 • CO2tP

COOLANT-

S

A ic°MPRESS°R

T3 T2.---

CONDENSER

REG HX

T5

T1

BOSCH

REACTOR

CONDENSATE

-

II

I

]

LIQ H20

P

-- COOLANT

S

FIGURE C-16

BOSCH PROCESS SUBSYSTEM SCHEMATIC

C-27


nH2,i - mH2,1/2.016

nc02, i - mc02,i/44.011

MWBDG - 16.043 YCH4 + 44.011YC02 + 2.016 YH2 + 28.011YCO

where: mH2,i - Mass flow of H2 entering Bosch system, pph

nH2,i - molar flow of H2 entering Bosch system, moles/hr

mc02, i - mass flow of CO2 entering Bosch system, pph

nc02, i - molar flow of CO2 entering Bosch system, pphYCH4 " mole fraction of methane in dry cond. exit gas =

.235

YC02 : mole fraction of CO2 in dry cond. exit gas =.163

YH2 " mole fraction of H2 in dry cond. exit gas : .327

YCO " mole fraction of CO in dry cond. exit gas - .275

MWBDG - molecular weight of bone dry cond. exit gas

The amount of carbon processed and water produced for a

quasi-equilibrium assumption is given by the following which isbased on the reaction formula:

If CO2 limiting:

mc, p - me02, i * MWc

mH20, p - 2 mc02, i * MWH20 + mH20, i

C-28

_ UNITEDTECHNOLOGIES_A_DB_@H

If H2 limiting:

SVHSER 10638

mc, p = mH2,i MWc/2

mH20, p = mH2,i MWH20 + mH20,i

where: MW c - molecular weight of carbon - 12.011 Ibm/mole

MWH20 - molecular weight of water - 18.016 Ibm/mole

MH20, i . mass flow of vapor and entrained liquid entering

Bosch system, Ibm/hr

mc, p - mass rte of carbon production, Ibm/hr

mH20, p - mass rate of water production, lbm/hr

Therefore, flow out of condenser is:

m3 = mr - mc, p - mH20, p

where: mr = recycle flow rate on more specifically the mass

flow at the compressor = 6.80 Ibm/hr

The temperature at the condenser exit is iterated upon. Its

initial value is assumed to be 20OF hotter than the inlet coolant

temperture:

T3 - Tcool + 20

C-29


The iteration begins with the calculationof the flow rate of bine

dry condenser exit gas

mBDG =

whe re:

I ÷

m3

MWH20 PH20

MWBDG PCOND - PH20

PH20 = Psat (T3)

PH20 = partial pressure of vapor leaving condenser, psia

PCOND = total pressure of recycle gas in condenser =

16.9 psia

mBD G = mass flow of bone dry gas leaving condenser, pph

Accordlngly, the flows out of the condenser and compressor are:

mBDG

nBDG =MWBDG

PH20

mH20, 3 =Pcond

mH20, 4 = mH20, 3 + mH20, 2

mH2, 3 = nBDG YH2 MWH2

mH2, 4 = mH2, 3 + mH2, 4

mc02, 3 = mBDG YC02

mc02, 4 = mc02, 3 + mc02, 4

mCH4, 3 = nBDG YCH4 MWCH4

mCH4, 4 = n_;H4, 3

mco, 3 = nBDG YCO MNco

mco, 4 =mco, 3

nBDG MWH20

C-30


The properties of the flow exiting the compressor are:

SVHSER 10638

Cp4 : (3.42 mH2,4 + 0.21 mc02, 4 + 0.55 mCH4, 4 + 0.25 mco,4

+ 0.49 mH20, 4 + 0.22 m02 + 0.299 mN2) / mr

MW4 mr I (mH2,4/2.016 +"_02,4/44.011 + mCH4,4/16.043

+ mc0,4/28.011 + mH20,4/18.06 + m02/32

+ mN2/28.088)

where:

Cp4

1,987

MW4

Cp4 = Specific heat of gas at compressor exit, BTU/Ibm-F

MW4 . Molecular weight of gat at compressive exit,

Ibm/mole

"1"4 = Ratio of constant pressure to constant volume

specific heats

m02 - Mass flow of oxygen in recycle gas = 0.0 Ibm/hr

mN2 = Mass flow of nitrogen in recycle gas = 0.0 lbm/hr

C-31

_ uNrrEDTECHNOLOGIES SVHSER 10638

The mixed temperature of inlet gases and the recycle gases exiting

condenser is given by:

T6 = [(mBDG 1CPBD G + 0.49 mH20,3) T3 + 0.21 mco 2 i + 3.42 mH2,i

+ 0.49 mH20,iv + 1.0 mH20,ie ] / (mr Cp41

CPBD G = [3.42 mH2,3 + 0.21 mc02, 3 + 0.55 mCH4, 3 + 0.25 mco,3+ 0.22 m02 ' + 0.299 mN2)/mBD G

where:

T6 - Mixed temperature of gases entering, compressor, F

mH20, iv " Mass flow of vapor entering system, pph

mH20, ie " Mass flow of entrained liquid entering system, pph

CPBDG - Specific heat of dry gas exiting condenser, Btu/Ibm-F

The energy required to raise the pressure of the recycle flow gases

across the compressor is given by:

IIp_ndlPr Y4-111Qc " mr R (TG + 460)'Y'4 ")r4

778 MW4 (Y4-1) _a

where: R - Universal gas constant - 1545 ft-lbf/mole-R

Pr - Reactor pressure : 24.3 psia

a " Aerodynamic efficiency of compressor = 1.0

Qc - Compressor energy into recycle gas, Btu/hr

C-32


The total power consumed by the compressor is given by:

Qc

w c -

_c 3.41

where: Wc . Power to run compressor, watts

c " Motor efficlency of compressor

Therefore, the heat lost to the ambient is:

Qa " 3.41 Wc - Qc

The heat of reaction In the reactor is:

Qr " 973 x mc02, i

Essentially, it is assumed that the input gases are

in ratio which then causes the mole fractions of the gases

remain constant In the recycle loop. The temperature out of

compressor is:

stoichiometric

to

the

Qc

T4 = T6 +mr CP4

C-33


The temperature out of the reactor is:

T I - TrQLR

mr Cp4

where: QLR " Heat loss from reactor - 0.0 Btu/hr

The temperature into the condenser is:

T2 - T1 -CHX (TI - T4)

where: {HX " Heat exchanger efficiency - 0.85

Finally, the temperature of the gases leaving the condenser is:

T3 - T2 - Ec (T2 - Tcool)

where: _c " Condenser efficiency - 0.90

This T3 is compared with the original gressed T3. If they agree

within 0.3 F, the iteration is complete; otherwise, this T3 is

tried as the next gress.

C.3.3 Static Feed Water Vapor Electrolysis {KOH)

The Static Feed Water Vapor Electrolysis subsystem uses KOH as the

medium for electrolysis to produce oxygen. This model is based on

the ELCELL subroutine in GI89A [2]. The following assumptions are

used:

(i) The unit is isothermal within the cells.

C-34


(2) Product gas streams exit at the prevailing cell temperature.

(3) The cell Faradaic efficiency is i00%; the cells are voltage

inefficient only.

(4) All cells are connected-in series, i.e., the same input

current passes through each ce11.

(s) The thermoneutral voltage is 1.48 volts; the voltage

efficiency is equal to the thermoneutral voltage divided by

the actual voltage.

The gas production is calculated as follows:

J - I/A

mH20, e - Nc 1/1350

mH2,p - MH20,e/ MWH20

no2,p = nH2,p/2

C-35


where: I = Input current to cells, amps

A = Area of one ce11, ft2

Nc = Number of cells

mH20, e " Mass flow of 02 consumed by electrolysis Ibm/hr

J = Cell current density, amps/ft 2

nH2 ' p = Molar flow of hydrogen produced, moles/hr

no2 ' p = Molar flow of oxygen produced, moles/hr

The details of the analytical

G189A manual for the subrouEine ELCELL.

of the energy required for electrolysis

the following equations and tables:

method are described fully in the

However, the calculation

is computed according to

First, the cell voltage at 150 amps/sq, ft. current density for any

cell temperature is

table:

Tc Vo(F) (Volts)

II0 1.660

120 1.620

130 1.575

140 1.550

150 1.530

160 1.500

170 1.475

180 1.465

190 1.450

determined by interpolation of the following

C-36


For cel] temperatures less than 110 F, the voltage is set to 1.70

volts.

Next, the effect of a current density different from 150 amps/sq.

ft. is found by interpolating the following table:

J Delta V/Delta J

(amps/ft) (VoIts/ASF)

0 0.01460100 0.00060200 0.00055300 0.00050400 0.00050500 0.00045600 0.00045

Then the following is used to calculate the cell voltage:

V (J-150)Vc - Vo + --_

The cell efficiency is:

= 1.48 100Vc

and is limited to a peak value of 99%.

Lastly, the energy required for electrolysis is given by:

Q - Nc I Vc 3.413

C.3.4 Plate Fin Condensin 9 Heat Exchanger

This subroutine models the performance for a plate fin condensing

heat exchanger. Basically, the program iterates on the condenser

C-37


C.3.4 Plate Fin Condensing Heat Exchanger (Continued)

SVHSER 10638

outlet temperature until the outlet temperature does not

from iteration to iteration.

First, the inlet dew point is calculated:

change

mv,jIx)i .....

mo,i

CO I Pt,i

Pv,i "i + O.622

Tdp,l " Tsat (Pv,i)

where: mv, i - Mass flow of inlet vapor, pph

mda,i - Mass f|ow of dry air, pph

_u i -In]et absolute humidity

PT,i " Inlet air total pressure, psia

Pvi " Inlet air partial pressure of water, psia

The initial guess at the exit temperature is one quarter of the way

from the coolant in|et temperature to the air inlet temperature:

Ta, e . Tc, i + i/4 (Tc,i + Ta, i)

From the exit temperature, the outlet absolute humidity and vapor

pressure are calculated:

C-38


Pv,e : Psat (Ta,e)

e = 0.622 Pv,erT - rv,e

The heat loads are then:

QL = Mda,i (_i -_e) hfg

Qs" ma,i Cp,a (Ta,i -Ta,e)

Qt " Qs + QL

where: hfg - Heat of vaporization, Btu/Ibm

QL " Latent heat, Btu/hr

Qs " Sensible heat, Btu/hr

Qt " Total heat loss, Btu/hr

ma, i - Total mass flow of air into Hx, Ibm/hr

The coolant exlt temperature Is:

Tc, e - Tc, i +

Qt

mc Cp,c

where: mc - Coolant flow, pph

Cp,c - Specific heat of water, Btu/Ibm-F

From here, various properties of the air and coolant are calculated

as a function of the average temperature. The properties and

nondimensional numbers calculated are:

C-39


K

Pr

Re

I Viscocity

- Thermal conductivity

- Prandtl number

. Reynolds number

Col I Colburn factor

Cmo d . Modified Colburn factor

SVHSER 10638

The conditions are shown in the listing presented in the User's

Manual [4]. Also shown there are various geometric dimensions such

as fin height.

The film coefficient is chosen as the maximum of the following two

equations:

h I 3.65 KID h

h = Cmo d Cp G Pr--6667

Overall fin efficiency is then computed from the following fin

equations:

C-40


where: h = Film coefficient

k = Therma! conductivity of fin

W = Fin thickness

L - Fin length

SVHSER 10638

k - tanh mLmL

where:

Af (l-k)

- 1- R-

Af = Surface area of fins only, ft2

A - Total exposed surface area, including the fins and

the unflnned primary surface, ft2

k = Fin effectiveness

= Total surface temperature effectiveness or

overall fin efficiency

The effective UA becomes:

UA = _ hA

The total effective dry UA is calculated as:

UAdry

1i

I I

UA--_+ UA-_

C-41


where: UAc - Cold side effective UA, Btu/hr-F

UAa - Hot or air side effective UA, Btu/hr-F

The pinch point temperatures for the air side and coolant side are

given by:

Tpp,a

UAc Tdp,i + Tdp,i - Tc, e Cp,c mc + ma,i Cp,a Ta,im

ma,i Cp,a + mc Cp,c UAa

UAc

The pinch point temperatures for the air and the coolant are those

which occur at the location where the wall temperature equals the

inlet dew point temperature:

Tpp,c - Tdp,i - UAa (Tpp,a - Tdp,i)

UAc

These above equations can be derived from the simultaneous solution

of the following two energy balances:

UAa (Tpp,a - Tdp,i) - UAc (Tdp,i - Tpp,c)

ma,i Cp,a (Tpp,a - Ta,i) = Mc Cp,c (Tpp,c - Tc,e)

The wet side and dry side log mean temperature differances are:

C-42


5YA[_DASSD

Tw,lm =

Td,lm -

(Ta,e - Tc,i) - (Tpp,a - Tpp,c )

Tpp,a Tpp,

(Tppa, - Tpp,c) - (Ta,i - Tc,e)

In ('Tpp,a- Tpp,c 1

_, Ta,i Tc,e /

SVHSER 10638

Now, the wet and dry section dry UA's are:

UAd,ws

mc (Tpp,c - Tc,l) UAc + Qt

Tw,lm UA---;

Qt UAc

UA---;+I

UAd,ds - mc (Tc,e - Tpp,c)

Td,lm

The total effective dry UA is:

UAd,to t - UAd,ws + UAd,ds

The air exlt temperature is iterated upon until:

UAd,tot " UAdry

C.3.5 Control

The control of the Space Station model is done in subroutine

GPOLYI. The following paragraphs describe the control laws used to

control:

C-43

'UNITEDTECHNOLOGIES SVHSER 10638

(a) Oxygen partial pressure

(b) Total cabin pressure

(c) Oxygen accumulator pressure

(d) Temperature control

(e) C02 accumu]ator exit flow control

(f) H2-C02 mix to C02 reduction unit

Oxygen partial pressure is controlled by using the same

as described in the original ESCM Model Description Document

The controller maintains oxygen partial pressure between 3.09

3.23 psia.

technique

[i].

and

Total cabin pressure is maintained by the addition of nitrogen.

The controller admits nitrogen to bring the pressure up to 14.813

psia only after the oxygen pressure is above 3.09 psia. The

original Model Description Document [I] should be seen for more

detail.

The oxygen accumulator pressure is maintained by addition of oxygen

from the oxygen generators as oxygen is drawn from the accumulators

to maintain cabin 02 partial pressure. The current to the oxygen

generators is regulated to each of the generators according to the

following law:

C-44 i


For P02 _ 1050

For P02 _ 950

For 950 P02 < 1050

I - 0.9 Inom

I - 1.11no m

I - Inom

SVHSER 10638

As the current is increased, the oxygen generation by

electrolysis unit increases.

the

For temperature control, the bypass flow around the condensing heat

exchanger is regulated. A proportional plus integral scheme is

used:

R - 0.05 E + _0.0001E dt

where: R - Fraction of flow to bypass Hx.

E - Temperature error - Tse t - Tac t

As more flow bypasses the Hx, the mixed flow after the Hx is

hotter.

Carbon dioxide removed from the air is sent to an accumulator.

Each C02 removal unit has its own accumulator in a nonbussed

system. The flow out of the accumulator is regulated to maintain

pressure in the accumulator above 21 psia. Essentially, the

average C02 removal rate during the past molecular sieve cycle is

used as the flow out of the accumulator for the present cycle.

C-45


$_AMDA@_D

SVHSER 10638

Lastly, the H2-C02 mixture into the C02 Reduction unit is regulated

to be stoichiometric by venting

produced by the oxygen generators.

amount to be vented is given by:I

excess hydrogen after being

The required H2 flow and the

mH2 - 2 mco 2

MWH2

MWc02

R - m im i - mH2

mi

where: mco 2 -

mH2 -

m I -

R -

Flow of C02 to reduction, pph

Stoichiometric flow of H2 to reduction, pph

Inlet f]ow to splitter, pph

Fraction of H2 inlet flow to be vented

C-46

; :,L,' ,,;r_ i'wfl" ill, ,r

1. Report No.

NASA CR-181738

4. Title and Subtitle

OPJGNVAL PAGE IS

',,.,,".-"._K _U&L[TY

Report Documentation Page

2. Government Accession No. 3. Recipient's Catalog No.

5. Report Date

Appendices to the Model Description Document for A

Computer Program for the Emulation/Simulation of a

Space Station Environmental Control and Life Support

System

7. Author(s)

James L. Yanosy

9. performing Organization NameandAddress

Hamilton Standard

Division of United Technologies Corporation

Windsor Locks, CT 06096

t2. Sponsoring Agency NameandAddress

NASA

Langley Research Center

Hampton, VA 23665-5225

September 1988

6. Performing Organization Code

8. Performing Organization Report No.

SVHSER 10638

10. Work Unit No.

506-49-31--01

11. Contract or Grant No.

NASI-17397

13. Type of Report and Period Covered

Contractor Report

14. Sponsoring Agency Code

15. Supplementary Notes

Langley Technical Monitors: John B. Hall, Jr., and Lawrence F. Rowell

I__ Description Document for the Emulation Simulation Computer Model was pub-

lished previously. The model consisted of a detailed model (emulation) of a SAWD

CO removal subsystem which operated with much less detailed (simulation) models of2

a cabin, crew, and condensing and sensible heat exchangers. The purpose was to

explore the utility of such an emulation/simulation combination in the design,

development, and test of a piece of ARS hardware - SAWD.

Extensions to this original effort are presented in the manual. The first extension

is an update of the model to reflect changes in the SAWD control logic which

resulted from test. In addition, slight changes were also made to the SAWD model to

permit restarting and to improve the iteration technique. The second extension is

the development of simulation models for more pieces of air and water processing

equipment. Models are presented for: EDC, Molecular Sieve, Bosch, Sabatier, a new

condensing heat exchanger, SPE, SFWES, Catalytic Oxidizer, and multifiltration. The

third extension is to create two system simulations using these models. _e first

system presented consists of one air and one water processing system. The second

system consists of a potential Space Station air revitalization system complete with

a habitat, laboratory, four modes, and two crews.

17. Key Words(SuggestedbyAuthor(s)) 18. Distribution Statement

Computer Simulation, Environmental Control Unclassified - Unlimited

Space Station, Life Support, Computer Subj. Cat. - 54

Modeling

19. SecurityClassif.(ofthisreport)

Unclassified

NASA FORM 1626 OCT 86

20. SecurityClassif.(ofthispage)

Unclassified

21. No. of pages

96

22. Price

A05

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